Mattress layer



FIG. 1 is a front perspective view of a mattress layer in accordance with the present invention;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a left view thereof; and,

FIG. 7 is a right view thereof. 

CLAIM We claim the ornamental design for a mattress layer, as shown and described. 